For high-value utilization of wheat germ, the effects of wheat germ-derived peptide ADWGGPLPH on the viability of osteoblast (OB) and osteoclast (OC) in an H₂O₂-induced oxidative stress model were investigated in OB-OC co-culture system. Flow cytometry, the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay and Annexin V-fluorescein isothiocyanate/propidium iodide (FITC/PI) double staining were used to clarify the effects of wheat germ-derived peptide on OB proliferation and apoptosis in oxidative stress environment. The effects of wheat germderived peptide on the differentiation of OB and OC in the co-culture system under oxidative stress were determined by using alkaline phosphatase (ALP) activity assay, enzyme-linked immunosorbent assay (ELISA) and tartrate resistant acid phosphatase (TRAP) staining. The results showed that wheat germ-derived peptide effectively prevented the increase of reactive oxygen species (ROS) in OB, and enhanced the ability of OB to protect against and scavenge free radicals by suppressing malondialdehyde (MDA) generation and increasing the activities of glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD). Wheat germ-derived peptide significantly inhibited the apoptosis of OB and improved its proliferation. Annexin V-FITC/PI double staining showed that the apoptosis rate was decreased from 12.4% to 5.3%, and the viability was increased from 60.4% to 92.8% (P < 0.01). In addition, wheat germ-derived peptide prevented the decrease of ALP activity, protein type Ⅰ collagen (COL-Ⅰ) and osteocalcin (OCN) expression, and increased OB mineralization from 21.3% to 84.3% (P < 0.01), thus maintaining OB differentiation and ensuring normal bone mineralization. Moreover, TRAP staining results showed that wheat germ-derived peptide effectively inhibited the over-differentiation of OC under oxidative stress condition, decreasing the relative positive area of OC from 376.4% to 128.1% (P < 0.01). In conclusion, this wheat germ-derived peptide has protective effects against H₂O₂-induced cellular oxidative damage in OB-OC co-culture system, thereby maintaining cellular homeostasis. This finding provides a certain theoretical basis for the development and utilization of wheat germ protein.

Bone loss caused by ageing has become one of the leading health risk factors worldwide. Wheat germ (WG) is consists of high amounts of bioactive peptides, polyunsaturated fatty acids, and dietary fibre. Currently, WG has been proven to possess strong antioxidant and anti-inflammatory properties. We recently explored the beneficial effects and relevant mechanisms of a WG-rich diet (2.5% and 5% WG, m/m) on bone homeostasis in aged rats. Our results showed that 5% WG supplementation for 12 months effectively attenuated ageing-induced microstructural damage and differentiation activity changes in the femur. The 5% WG supplementation also significantly increased the levels of total antioxidant capacity (T-AOC), glutathione peroxidase (GSH-Px) (P < 0.01), and superoxide dismutase (SOD) (P < 0.05), and decreased inflammatory cytokine levels (tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6)) (P < 0.01). Furthermore, the WG-rich diet reshaped the composition of the gut microbiota, enhancing short-chain fatty acids (SCFAs)-producing microbes and reducing inflammation-related microbes. In addition, metabolomics analysis showed that 5% WG supplementation improved plasma metabolites related to bone metabolism. Conclusively, our study purports long-term WG-rich diet may preserve bone homeostasis by regulating gut microbiota and plasma metabolites in aged rats.